Curtain hook



FIG. 1 is a perspective view of a curtain hook showing my new design;

FIG. 2 is a left side view thereof, the opposite side being a mirror image of the side shown;

FIG. 3 is a front elevational view thereof; and,

FIG. 4 is a top plan view thereof. 

The ornamental design for a curtain hook, as shown and described. 